With mechanical waves, what is moving and what stays in roughly the same place?

The boy of mass 30 kg is at r1= 2 meters from the fulcrum. of the girl is 45 kg, at what r2 must she sit so that they are balanced ?

The passage that directs air to the lungs is called a. diaphragm. b. larynx. c. bronchi. d. pharynx.

The image shows the positions of a car on a roller coaster track. arrange the cars in order based on their gravitational potential energy. begin with the lowest potential energy and end with the highest.